A method of forming a laser on silicon using aspect ratio trapping (ART) growth. The method may include; forming a first insulator layer on a substrate; etching a trench in the first insulator layer exposing a top surface of the substrate; forming a buffer layer in the trench using ART growth; forming a laser on the buffer layer, the laser includes at least an active region and a top cladding layer; and forming a top contact on the top cladding layer and a bottom contact on the substrate.